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<head><meta charset="utf-8"><title>Undefined OpCode · project-inline-asm · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/index.html">project-inline-asm</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html">Undefined OpCode</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208111108" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> rylev <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208111108">(Aug 26 2020 at 15:57)</a>:</h4>
<p>Sorry if this is the wrong place for this question. I'm looking to add __fastfail support in Rust for the ARM Windows targets (32/64). I need to emit a special opcode (Opcode 0xDEFB). How would I do this using llvm_asm!?</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208111758" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Amanieu <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208111758">(Aug 26 2020 at 16:02)</a>:</h4>
<p><code>.inst 0xdefb</code></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112030" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> rylev <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112030">(Aug 26 2020 at 16:04)</a>:</h4>
<p>Thanks!</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112054" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112054">(Aug 26 2020 at 16:05)</a>:</h4>
<p><span class="user-mention" data-user-id="143274">@Amanieu</span> Would the usual .byte also work?</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112281" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Amanieu <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112281">(Aug 26 2020 at 16:06)</a>:</h4>
<p>Sure but that doesn't mark those bytes as instruction in the debuginfo, so they disassemble as data instead of an instruction.</p>



<a name="208112463"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112463" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112463">(Aug 26 2020 at 16:08)</a>:</h4>
<p>Ah, interesting!</p>



<a name="208112489"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112489" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112489">(Aug 26 2020 at 16:08)</a>:</h4>
<p>Today I learned.</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/216763-project-inline-asm/topic/Undefined%20OpCode/near/208112579" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Amanieu <a href="https://rust-lang.github.io/zulip_archive/stream/216763-project-inline-asm/topic/Undefined.20OpCode.html#208112579">(Aug 26 2020 at 16:09)</a>:</h4>
<p><a href="https://developer.arm.com/documentation/dui0803/j/accessing-and-managing-symbols-with-armlink/about-mapping-symbols">https://developer.arm.com/documentation/dui0803/j/accessing-and-managing-symbols-with-armlink/about-mapping-symbols</a></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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